1. Field of the Invention
The present invention generally relates to systems and methods for high sensitivity repeater defect detection.
2. Description of the Related Art
The following description and examples are not admitted to be prior art by virtue of their inclusion in this section.
Inspection processes are used at various steps during a semiconductor manufacturing process to detect defects on wafers to promote higher yield in the manufacturing process and thus higher profits. Inspection has always been an important part of fabricating semiconductor devices such as ICs. However, as the dimensions of semiconductor devices decrease, inspection becomes even more important to the successful manufacture of acceptable semiconductor devices because smaller defects can cause the devices to fail.
Some current inspection methods detect repeater defects on wafers to thereby detect defects on reticles. For example, if a defect is detected repeatedly (“a repeater defect”) at multiple locations on a wafer corresponding to the same location on a reticle, the defects may be caused by the reticle itself. Therefore, repeater defects may be analyzed to determine if they are caused by reticle defects, rather than some other cause.
In general, repeater defect detection (RDD) is performed as a wafer post-processing (PP) operation. For example, the inspection tool may perform normal die-to-die defect detection (DD), and after all wafer defects are reported, the RDD may be performed in a user interface in a post-processing step rather than in a different computer component of the inspection tool. The repeater defects are defined as defects positioned at the same location (within a certain tolerance) in several dies.
There are, however, several disadvantages to the currently used methods and systems for RDD. For example, in order to find weak repeater defects, a substantially hot defect detection needs to be performed. A majority of the detected events are not repeaters and are filtered by RDD. The problem is the tool has a limited capacity for defects stored in the lot result due to band-width (of the internal network of the inspection tool) and disk space. Location is a substantially strong filter that eliminates a majority of the events in the lot results, but for the weak repeaters, the inspection cannot be run hot enough to save all of the candidate defects.
Accordingly, it would be advantageous to develop systems and methods for detecting repeater defects on a wafer that do not have one or more of the disadvantages described above.